On Fri, Jun 18, 2021 at 02:15:31PM +0800, Huang Ying wrote:

From: Yang Shi <redacted>

The migrate_pages() returns the number of pages that were not migrated,
or an error code.  When returning an error code, there is no way to know
how many pages were migrated or not migrated.

In the following patch, migrate_pages() is used to demote pages to PMEM
node, we need account how many pages are reclaimed (demoted) since page
reclaim behavior depends on this.  Add *nr_succeeded parameter to make
migrate_pages() return how many pages are demoted successfully for all
cases.

Signed-off-by: Yang Shi <redacted>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: "Huang, Ying" <redacted>
Reviewed-by: Yang Shi <redacted>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Wei Xu <weixugc@google.com>
Cc: Dan Williams <redacted>
Cc: David Hildenbrand <redacted>
Cc: osalvador <osalvador@suse.de>

I thought we all agreed on making nr_succeed an optional argument [1].
It reduced the churn quite a lot.

[1] https://patchwork.kernel.org/comment/24104453/


-- 
Oscar Salvador
SUSE L3